Method and apparatus for transmitting/receiving control information in a wireless communication system

ABSTRACT

A method and apparatus for receiving control information in a digital broadcasting/communication system. The method includes receiving signaling information having a fixed number of bits in a coded block of a received frame; and decoding signaling information having a variable number of bits in at least one coded block of the received frame, using the signaling information having the fixed number of bits. The signaling information having the fixed number of bits includes information about a number of Radio Frequency (RF) channels, and the signaling information having the variable number of bits includes information representing a frequency for each of the RF channels, respectively.

PRIORITY

This application is a Continuation of U.S. application Ser. No.12/396,644, which was filed in the U.S. Patent and Trademark Office onMar. 3, 2009, and claims priority under 35 U.S.C. §119(a) to KoreanPatent Application Serial No. 10-2008-0019651, which was filed in theKorean Intellectual Property Office on Mar. 3, 2008, the entiredisclosure of each of which is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a method and apparatus fortransmitting/receiving control information in a wireless communicationsystem. More particularly, the present invention relates to a method andapparatus for transmitting/receiving physical layer control informationin a wireless communication system.

2. Description of the Related Art

FIG. 1 illustrates a conventional transmission scheme for a frameincluding control information in a wireless communication system,especially in a wireless digital broadcasting system.

Referring to FIG. 1, reference numeral 101 denotes one frame. The frame101 includes a preamble 102, Layer 1 (L1) signaling information 103,Layer 2 (L2) signaling information 104, and at least one Physical LayerPipe (PLP) 105 to 107. The control information can be delivered in thepreamble 102, the L1 signaling information 103, and the L2 signalinginformation 104, and data is carried in the PLPs 105 to 107.

The preamble 102 is used for time and frequency synchronization andframe synchronization at a receiver. The L1 signaling information 103 isreferred to as P2 because it is transmitted in a P2 symbol. P2represents L1, i.e. physical layer signaling information.

The L1 signaling information 103 includes static, configurable, anddynamic information as indicated by reference numerals 108, 109 and 110,respectively. The static information 108 is almost constant in time,including information about a cell Identifier (ID), a network ID, thenumber of Radio Frequency (RF) channels, a frame length, and thepositions of pilot subcarriers. The configurable information 109 doesnot change in every frame, but includes information that can beconfigurable in an upcoming frame. Therefore, the configurableinformation 109 includes information about a service ID, a modulationscheme, and a code rate used for transmitting service data.

The dynamic information 100 may vary in every frame, including theposition of each PLP carrying service data in a current frame, i.e. thestart and end of each PLP. In FIG. 1, the L2 signaling information 104is signaling information about Layer 2 (L2), that is, a Medium AccessControl (MAC) layer. A PLP carrying the L2 signaling information 104 isreferred to as PLP 0. PLP 0 includes information about the connectionbetween a PLP and a broadcasting service, describing a PLP in which aparticular service is received. The PLPs 105 to 107, PLP 1 to PLP N,convey at least one service channel. As the PLPs 105 to 107 carry actualbroadcasting data, they are also referred to as data PLPs.

To receive a specific broadcasting service channel, a receiver acquiresframe synchronization from the preamble 102 and achieves informationabout a data transmission scheme and a frame length from P2, that is,the L1 signaling information 103. The receiver then detects PLPscarrying the intended service channel from PLP0, that is, the L2signaling information 104, and receives broadcasting data in the PLPs.

In the case of control information such as signaling information, it mayinclude a large number of dummy bits during encoding in the wirelesscommunication system. These dummy bits dissipate communicationresources. Accordingly, there exists a need for a method for encodingcontrol information to efficiently use communication resources.

SUMMARY OF THE INVENTION

An aspect an embodiment of the present invention is to address at leastthe problems and/or disadvantages and to provide at least the advantagesdescribed below. Accordingly, an aspect of an embodiment of the presentinvention is to provide a method for generating a plurality of codedblocks by efficiently encoding control information and atransmission/reception method and apparatus using the same in a wirelesscommunication system.

Another aspect of an embodiment of the present invention provides amethod for generating a plurality of coded blocks by efficiently LowDensity Parity Check (LDPC)-encoding control information and atransmission/reception method and apparatus using the same in a wirelesscommunication system.

A further aspect of an embodiment of the present invention provides amethod for generating coded blocks distinguishably according to the typeof control information and a transmission/reception method and apparatususing the same in a wireless communication system.

In accordance with an aspect of the present invention, a method isprovided for receiving control information in a digitalbroadcasting/communication system. The method includes receivingsignaling information having a fixed number of bits in a coded block ofa received frame; and decoding signaling information having a variablenumber of bits in at least one coded block of the received frame, usingthe signaling information having the fixed number of bits. The signalinginformation having the fixed number of bits includes information about anumber of RF channels, and the signaling information having the variablenumber of bits includes information representing a frequency for each ofthe RF channels, respectively.

In accordance with another aspect of the present invention, an apparatusis provided for receiving control information in a digitalbroadcasting/communication system. The apparatus includes a receiver forreceiving a frame including signaling information for a physical layer;a decoder for decoding received information using a predetermined codingscheme; and a controller for controlling the decoder to decode signalinginformation having a fixed number of bits included in the signalinginformation for the physical layer and to decode signaling informationhaving a variable number of bits included in the signaling informationfor the physical layer using the decoded signaling information havingthe fixed number of bits. The signaling information having the fixednumber of bits includes information about a number of RF channels, andthe signaling information having the variable number of bits includesinformation representing a frequency for each of the RF channels,respectively.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features and advantages of certainembodiments of the present invention will be more apparent from thefollowing detailed description taken in conjunction with theaccompanying drawings, in which:

FIG. 1 illustrates a conventional transmission scheme for a frameincluding control information in a wireless communication system,especially in a wireless digital broadcasting system;

FIG. 2 illustrates a method for encoding control information in awireless communication system to which the present invention is applied;

FIG. 3 illustrates a control information encoding method in the wirelesscommunication system according to an embodiment of the presentinvention;

FIG. 4 illustrates the structures of first and second codewords ascontrol information encoded in the method of FIG. 3;

FIG. 5 is a flowchart illustrating a method for transmitting controlinformation in a transmitter in the wireless communication systemaccording to an embodiment of the present invention;

FIG. 6 is a flowchart illustrating a method for receiving controlinformation in a receiver in the wireless communication system accordingto an embodiment of the present invention;

FIG. 7 is a block diagram of the transmitter in the wirelesscommunication system according to an embodiment of the presentinvention; and

FIG. 8 is a block diagram of the receiver in the wireless communicationsystem according to an embodiment of the present invention.

Throughout the drawings, the same drawing reference numerals will beunderstood to refer to the same elements, features and structures.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

The matters defined in the description such as a detailed constructionand elements are provided to assist in a comprehensive understanding ofvarious embodiments of the invention. Accordingly, those of ordinaryskill in the art will recognize that various changes and modificationsof the embodiments described herein can be made without departing fromthe scope and spirit of the invention. Also, descriptions of well-knownfunctions and constructions are omitted for clarity and conciseness.

FIG. 2 illustrates a method for encoding control information in awireless communication system to which the present invention is applied.Specifically, the control information is the L1signaling informationillustrated in FIG. 1.

Referring to FIG. 2, L1 signaling information further includes L1pre-signaling information 202 in addition to L1 static information 203,L1 configurable information 204, and L1 dynamic information 205 thathave been described before with reference to FIG. 1. The L1pre-signaling information 202 provides information about a transmissionscheme for the L1 static information 203, the L1 configurableinformation 204, and the L1 dynamic information 205. That is, the L1pre-signaling information 202 indicates subcarriers, modulation schemes(Quadrature Phase Shift Keying (QPSK), 16-ary Quadrature AmplitudeModulation (16 QAM), 64 QAM, etc.), and code rates used for the L1static information 203, the L1 configurable information 204, and the L1dynamic information 205. While specific numbers of bits are describedfor the L1 pre-signaling information 202, the L1 static information 203,the L1 configurable information 204, and the L1 dynamic information 205,they are mere examples to which the present invention is not limited.

A transmitter creates a codeword by LDPC-decoding the L1 pre-signalinginformation 202 independently, as indicated by reference numeral 206 andanother codeword by LDPC-encoding the L1 static information 203, the L1configurable information 204, and the L1 dynamic information 205collectively, as indicated by reference numeral 207. For the input of arelatively small number of input bits, for example, 200 to 300 bits, theLDPC code generally has poor coding performance.

In the illustrated case of FIG. 2, for the L1 pre-signaling information202, no more than 41 input bits are added with 227 dummy bits and 32Cyclic Redundancy Check (CRC) bits. The resulting 300 bits are encodedinto one codeword. As described above, as many as 227 bits are used asdummy bits to transmit 73-bit information including the 41-bit L1pre-signaling information and the 32-bit CRC, which is very inefficient.

In accordance with a control information encoding method of the presentinvention, a first codeword is generated by encoding the L1pre-signaling information 202 and predetermined default information ofthe L1 static information 203 (referred to as default L1 staticinformation) and a second codeword is generated by encoding theremaining additional L1 static information, the L1 configurableinformation 204, and the L1 dynamic information 205. Notably, theremaining additional L1 static information is optional in the presentinvention.

FIG. 3 illustrates a control information encoding method in the wirelesscommunication system according to an embodiment of the presentinvention.

Referring to FIG. 3, for encoding control information such as L1signaling information, a first codeword 307 is generated by encoding L1pre-signaling information 302 and default L1 static information 303extracted from L1 static information. An example of the default L1static information 303 will be described in detail with reference toFIG. 4. The input of the L1 static information for the first codeword307 is for improving performance by decreasing dummy bits considerably,compared to the conventional technology. The reason for inputting thedefault L1 static information 303 is to maintain the amount and type ofinput information of the first codeword.

A second codeword 308 is generated by encoding additional L1 staticinformation 304, L1 configurable information 305, and L1 dynamicinformation 306. The additional L1 static information 304 is optional,which will be described in detail with reference to FIG. 4. In FIG. 3,LDPC coding is adopted for creating the first and second codewords 307and 308, by way of example.

FIG. 4 illustrates the structures of the first and second codewords ascontrol information encoded in the method of FIG. 3.

Referring to FIG. 4, reference numeral 403 denotes an example of L1pre-signaling information and default L1 static information. TimeFrequency Slicing (TFS) represents transmission of one PLP on aplurality of Radio Frequency (RF) channels. In Table 403, NUM_RF at thestart of fields indicated by an arrow 406 indicates the number of RFchannels carrying one PLP. When one PLP is transmitted on a plurality ofRF channels, that is, TFS mode is used, NUM_RF is greater than 1. If onePLP is transmitted on one RF channel, NUM_RF is 1. There are as manymain RF_Frequency fields as the value of NUM_RF. RF_Frequency indicatesan RF frequency, usually occupying 32 bits. In the present invention,the first of one or more RF_Frequency fields is included in the firstcodeword. If NUM_RF is greater than 1, as many RF_Frequency fields as“NUM_RF-1” can be included in the second codeword. This configuration ofthe input information of each codeword can fix the bit numbers and typesof the 30 input information of the first codeword.

Main fields of the L1 pre-signaling information listed in Table 403 are“TYPE” indicating the type of a stream transmitted in a frame, “L1_COD”indicating the code rate of Part II information 402, “L1_MOD” indicatingthe modulation scheme of the Part II information 402, “L1_FEC_TYPE”indicating an L1 Forward Error Correction (FEC) type used for the PartII information 402 (e.g. a 16 k LDPC block), “L1_P_SIZE” indicating thesize of the coded and modulated Part II information 402, “BW_EXT” is anindicator specific to a geographical cell in a network, “NETWORK_ID”identifying a current network, “T2_SYSTEM_ID” identifying a system, and“RF_IDX” is the index of an RF channel.

Reference numeral 407 denotes another example of the first and secondcodeword configuration. In Table 403, FEF is a field indicating whethera Further Extension Frame (FEF) is used. An FEF is a frame defined toallow some frame to be transmitted in a future technology. If FEF is 0,an FEF is not used in the current system. If FEF is 1, an FEF is used inthe current system. Control information about Further Extension Frame isadded in Table 404. As noted from Table 403, the input information ofeach codeword is configured such that only necessary information isincluded in the first codeword when an FEF is not used and additional L1static information is included in the second codeword when an FEF isused. Hence, the input information of the first codeword is constant inbit number and type.

Main fields of L1 configurable information and L1 dynamic information ofPart II listed in Table 405 are “MUM_PLP” indicating the number of PLPstransmitted in a (super)frame, “PLP_ID” is an Identification (ID)specific to a PLP, “PLP_CO” indicating the code rate of the PLP,“PLP_MOD” indicating the modulation scheme of the PLP, “PLP_FEC_TYPE”indicating an FEC type used for the PLP, “PLP_NUM_BLOCKS” indicating thenumber of FEC blocks included in an interleaved frame of the currentPLP, and “PLP_START” indicating the start position of the PLP in thecurrent PLP.

FIG. 5 is a flowchart illustrating a method for transmitting controlinformation in a transmitter in the wireless communication systemaccording to an exemplary embodiment of the present invention.

Referring to FIG. 5, the transmitter generates P2 information (L1pre-signaling information, L1 static information, L1 configurableinformation, and L1 dynamic information) as control information for acurrent frame in step 501. The transmitter generates a coded block as afirst codeword (Part I) by LDPC-encoding the L1 pre-signalinginformation and default L1 static information having a fixed number ofbits among the determined control information and transmits the firstcodeword in step 502. In step 503, the transmitter determines whetherthe generated control information includes additional L1 staticinformation. In the absence of the additional L1 static information, thetransmitter generates a codeword being a coded block by LDPC-encodingthe L1 configurable information and L1 dynamic information having avariable number of bits and transmits the codeword in step 504. If theL1 configurable information and L1 dynamic information have a largenumber of bits, they can be transmitted in a plurality of code blocks,i.e. in a plurality of codewords.

In the presence of the additional L1 static information in step 503, thetransmitter generates a codeword by LDPC-encoding the additional L1static information together with the L1 configurable information and theL1 dynamic information and transmits the codeword in step 505. If thesum of the L1 configurable information and the L1 dynamic information isa large number of bits, they can be transmitted in a plurality ofcodewords. After step 504 or 505, the transmitter repeats the aboveoperation for a next frame in step 506.

FIG. 6 is a flowchart illustrating a method for receiving controlinformation in a receiver in the wireless communication system accordingto an embodiment of the present invention.

Referring to FIG. 6, the receiver acquires L1 pre-signaling informationand default L1 static information by decoding the coded block (LowDensity Parity Check (LDPC) block) of a first codeword in a receivedcurrent frame in accordance with predetermined subcarriers, code rate,and modulation scheme in step 601. In step 602, the receiver determines,based on the acquired information, whether a plurality of RF channels oran FEF is used. The determination of step 602 is about whetheradditional L1 static information exists. If additional L1 staticinformation does not exist in step 602, the receiver receives a secondcodeword of Part II in the current frame using the positions ofsubcarriers, the code rate, and the modulation scheme of Part IIacquired from the L1 pre-signaling information and acquires L1configurable information and L1 dynamic information from the secondcodeword of Part II in step 603. If determining that the additional L1static information exists in step 602, the receiver receives a secondcodeword of Part II in the current frame using the positions ofsubcarriers, the code rate, and the modulation scheme of Part IIacquired from the L1 pre-signaling information and acquires theadditional L1 static information, the L1 configurable information, andthe L1 dynamic information from the second codeword of Part II in step604. In step 605, the receiver repeats the above operation for a nextframe.

FIG. 7 is a block diagram of the transmitter in the wirelesscommunication system according to an embodiment of the presentinvention.

Referring to FIG. 7, a transmitter 700 includes a transmission databuffer 701, a scheduler 702, a control information generator 703, anLDPC encoder 704, a transmission part 705, and a controller 706. Inaccordance with the present invention, control information, that is,physical layer signaling information transmitted from the transmitter700 is divided into L1 pre-signaling information with a fixed number ofbits, and L1 configurable information and L1 dynamic information with avariable number of bits. The L1 variable information and the L1 dynamicinformation are referred to as L1-post signaling information.

The transmission data buffer 701 buffers service data (i.e. PLPs) to betransmitted on a plurality of broadcasting service channels, when abroadcasting service is provided in the wireless communication system.The scheduler 702 performs a predetermined scheduling operation based oninformation about the buffered data received from the transmission databuffer 701. The scheduling operation involves determining the L1pre-signaling information, the L1 configurable information, and the L1dynamic information as control information to be transmitted in a frame.The control information generator 703 receives the result of thescheduling operation and generates field values for the L1 pre-signalinginformation, the L1 configurable information, and the L1 dynamicinformation that have been described in detail with reference to FIG. 4.The LDPC encoder 704 receives the control information from the controlinformation generator 703, generates a coded block (LDPC block) from thesignaling information with the fixed number of bits and generates atleast one coded block from the signaling information with the variablenumber of bits. The transmission part 705 transmits the LDPC blocksreceived from the LDPC encoder 704 according to predetermined subcarrierpositions, code rate, and modulation scheme. The controller 705 providesoverall control to the transmitter 700 in order to generate and transmitLDPC blocks in the method of FIG. 5.

FIG. 8 is a block diagram of the receiver in the wireless communicationsystem according to an embodiment of the present invention.

Referring to FIG. 8, a receiver 800 includes a control informationreceiver 801, an LDPC decoder 802, a control information analyzer 804,and a controller 803. The control information receiver 801 receivescontrol information, that is, L1 signaling information including L1pre-signaling information, L1 configurable information, and L1 dynamicinformation according to predetermined subcarrier positions, code rate,and modulation scheme and demodulates the L1 signaling information. TheLDPC decoder 802 decodes the demodulated L1 signaling information in themethod described in FIG. 6 and outputs the decoded information to thecontrol information analyzer 804 which analyzes the decoded controlinformation. The controller 803 provides overall control to the receiver800 to receive and decode LDPC blocks in the method of FIG. 6.

As is apparent from the above description, the embodiments of thepresent invention can transmit and receive control information moreefficiently by decreasing the number of dummy bits, when the controlinformation is encoded and transmitted. Especially when controlinformation, that is, physical layer signaling information istransmitted in a plurality of LDPC codewords, a codeword having a fixednumber of bits is transmitted and received according to the types ofcontrol information. Therefore, a transmitter and a receiver aresimplified in structure.

Embodiments of the present invention can also be embodied ascomputer-readable codes on a computer-readable recording medium. Thecomputer-readable recording medium is any data storage device that canstore data which can thereafter be read by a computer system. Examplesof the computer-readable recording medium include, but are not limitedto, read-only memory (ROM), random-access memory (RAM), CD-ROMs,magnetic tapes, floppy disks, optical data storage devices, and carrierwaves (such as data transmission through the Internet via wired orwireless transmission paths). The computer-readable recording medium canalso be distributed over network-coupled computer systems so that thecomputer-readable code is stored and executed in a distributed fashion.Also, function programs, codes, and code segments for accomplishing thepresent invention can be easily construed as within the scope of theinvention by programmers skilled in the art to which the presentinvention pertains.

While the invention has been shown and described with reference tocertain embodiments of the present invention thereof, it will beunderstood by those skilled in the art that various changes in form anddetails may be made therein without departing from the spirit and scopeof the present invention as defined by the appended claims and theirequivalents.

What is claimed is:
 1. A method for receiving control information in adigital broadcasting/communication system, the method comprising thesteps of: receiving signaling information having a fixed number of bitsin a coded block of a received frame; and decoding signaling informationhaving a variable number of bits in at least one coded block of thereceived frame, using the signaling information having the fixed numberof bits, wherein the signaling information having the fixed number ofbits includes information about a number of Radio Frequency (RF)channels, and the signaling information having the variable number ofbits includes information representing a frequency for each of the RFchannels, respectively.
 2. The method of claim 1, wherein the signalinginformation having the fixed number of bits includes Layer 1 (L1)pre-signaling information that remains constant in signaling informationfor a physical layer.
 3. The method of claim 2, wherein the L1pre-signaling information includes information indicating at least oneof subcarriers, a modulation scheme, and a code rate used fortransmission of the signaling information having the variable number ofbits.
 4. The method of claim 1, wherein the frame includes service dataand the signaling information having the variable number of bitsincludes information required for receiving the service data.
 5. Themethod of claim 1, wherein the signaling information having the fixednumber of bits includes information indicating whether a FurtherExtension Frame (FEF) is used.
 6. The method of claim 1, wherein thesignaling information having the fixed number of bits includesinformation about a cell IDentifier (ID), a network ID, a system ID, andan RF index.
 7. The method of claim 1, wherein the frame includes atleast one Physical Layer Pipe (PLP) as service data, and when the atleast one PLP is transmitted on a plurality of RF channels, thesignaling information having the variable number of bits includesinformation about frequencies of other RF channels except for afrequency of a first RF channel.
 8. The method of claim 1, wherein thesignaling information having the variable number of bits includesinformation related to a reserved Further Extension Frame (FEF).
 9. Themethod of claim 1, wherein the coded block and the at least one codedblock are separately Low Density Parity Check (LDPC)-coded blocks. 10.An apparatus for receiving control information in a digitalbroadcasting/communication system, the apparatus comprising: a receiverfor receiving a frame including signaling information for a physicallayer; a decoder for decoding received information using a predeterminedcoding scheme; and a controller for controlling the decoder to decodesignaling information having a fixed number of bits included in thesignaling information for the physical layer and to decode signalinginformation having a variable number of bits included in the signalinginformation for the physical layer using the decoded signalinginformation having the fixed number of bits, wherein the signalinginformation having the fixed number of bits includes information about anumber of Radio Frequency (RF) channels, and the signaling informationhaving the variable number of bits includes information representing afrequency for each of the RF channels, respectively.
 11. The apparatusof claim 10, wherein the signaling information having the fixed numberof bits includes Layer 1 (L1) pre-signaling information that remainsconstant in the signaling information for the physical layer.
 12. Theapparatus of claim 11, wherein the L1 pre-signaling information includesinformation indicating at least one of subcarriers, a modulation scheme,and a code rate used for transmission of the signaling informationhaving the variable number of bits.
 13. The apparatus of claim 10,wherein the frame includes service data and the signaling informationhaving the variable number of bits includes information required forreceiving the service data.
 14. The apparatus of claim 10, wherein thesignaling information having the fixed number of bits includesinformation indicating whether a Further Extension Frame (FEF) is used.15. The apparatus of claim 10, wherein the signaling information havingthe fixed number of bits includes information about a cell IDentifier(ID), a network ID, a system ID, and an RF index.
 16. The apparatus ofclaim 10, wherein the frame includes at least one Physical Layer Pipe(PLP) as service data, and when the at least one PLP is transmitted on aplurality of RF channels, the signaling information having the variablenumber of bits includes information about frequencies of other RFchannels except for a frequency of a first RF channel.
 17. The apparatusof claim 10, wherein the signaling information having the variablenumber of bits includes information related to a reserved FurtherExtension Frame (FEF).
 18. The apparatus of claim 10, wherein thedecoder Low Density Parity Check (LDPC)-decodes the signalinginformation having the fixed number of bits.